Made edits to the MarkovGraph lab.
A few more edits to the MarkovGraph lab. Sorry, Fredo the Frog.
Minor edits on the complexity lab.
Another minor change to the complexity lab (so that the readers are not
misled about the complexity of matrix inversion).
Merge pull request #278 from abefrandsen/vol_1_edits

Made edits to the MarkovGraph lab.